Production of liquid drying oil polymer



March 11, 1958 w. w. cRoUm-s PRODUCTION OF LIQUID DRYINO O11, POLYMER 2Sheets-Sheet l Filed Oct. 27, 1952 mocpw 9.2.20

ATTORNEYS March H, 1958 Filed OGI'.. 27. 1952 PRESSURE, PSIG w. w.@ROUGH zzaszl PRODUCTION OF LIQUID DRYING OIL POLYMER 2 Sheets-Shet 2VAPOR PRESSURE OF SOLUTION OF I.3BUTADIENE IN N-HEPTANE TEMP. 202FBUTADIENE CONCENTRATION, WEIGHT INVENTOR. W.\ /V,CROUCH BY ,iwf-91%ATTORN EYS United States Patent G PRODUCTION OF LIQUID DRYIN G OILPOLYMER Willie W. Crouch, Bartlesville, Okla., assigner to PhillipsPetroleum Company, a corporation of Delaware Application October 27,1952, Serial No. 317,051

3 Claims. (Cl. 260-680) When operating a continuous process for theproduci tion of a liquid polybutadiene drying oil employing a singlereactor a portion of the butadiene from the feedstock passes from thereactor in an unused state. The quantity of unreacted `butadiene inthereactor ellluent depends uponfactors such as rate 0f reaction andresial dence time. Another important factor affecting the quantity ofunreacted butadiene in the effluent is the severtiy of agitation.Vigorous agitation of the reaction mixture is necessary. By virtue ofsaid vigorous agitation and the continuous addition of fresh feedmaterial to the reaction zone it is inevitable that some butadiene,generally more than is desirable, finds its way into the continuouslywithdrawn reaction zone eiuent. I have discovered that agitation of thesystem is unnecessary other than at or in the immediate vicinity of thepoint where the catalyst is introduced, such agitation being requiredonly to initiate the polymerization. My invention is directed tocompensating for undesirably large amounts of unreacted butadiene in theeiiiuent from a single continuous reaction zone wherein polybutadiene isproduced and comprises,-

broadly, passing said efliuent to a second relatively quiescent reactionzone where the butadiene content of the effluent, on a catalyst andpolymer free basis, is reduced at least to 1.5 weight percent and in allinstances reduced by at least 50 percent. My invention is particularlyuseful` when a butadiene-butylene mixture is employed as feedstock andpurification of the residual butylene is necessary so that it can beused for other purposes, viz., alkylation in the production of aviationgasoline,` etc. Also, more complete utilization of the butadiene in thefeed is effected.

In the present invention the quiescent zone comprises an elongatedvessel, preferably cylindrical and having a length to diameter ratio inthe range of 2:1 to 100:1 and can comprise a length of pipe or a coil.The vessel can be horizontally or vertically disposed. If the tinelydivided metallic catalyst as hereafter disclosed tends `to settlefrornthe reaction mixture, it will be preferred that the reaction vesselbe vertically disposed. However, due` to the fine dispersion of thecatalyst particles approaching colloidal size, the problem of settlingwill not be serious,.andxa horizontally disposed vessel canv be employedwithout difficulty. The volume of the `quiescentzoneis sufficient toallow a residence time therein in `thevrangeof 5minutes to 5 hours, thepreferred residence time beingin the .rangeof 10 to 45 *minutes` In t'solvents such as benzene, toluene and. xylene.

2,826,6Zl Patented Mar. 11, 1958 ICC continuous operation no agitationis provided in the quiescent zone other than the minor inherentagitation due to the ilow of liquids through said zone.

The presentprocess is an improvement over the process disclosed in myaforementioned copending application especially when operatingcontinuously with an impure butadiene feed. The feed which isparticularly useful in the process of the `present invention comprises abutylene-butadiene mixturecontaining `about 20 to 50 weight percentbutadiene with the remainder predominantly various'butenes.' Whenemploying such a feedstock in accordance with my invention the residualbutylene stream, after catalyst separation, is purified to a degreesufficient for use in other `proceses, such as alkylation andsubstantially all the butadiene is utilized in the production ofpolybutadiene. Feed stocks of this nature are readily availablecommercially and represent a comparatively cheap source of butadiene.Such feed stocks are obtained by separating theCl fraction of theproducts from the 'catalytic crackngj' of petroleum hydrocarbons as wellas by the catalytic dehydrogenation of n-butane. The chargestreamsapplicable for use in the process should be substantially free ofacetylenes which tend to poison the `catalyst andreduce the activitythereof.

` The use .of additional solvent when employing a butylene-butadiene'feedistream is optional since such a feed stream will normally contain)substantial amounts of material whichwillactas `asolvent such as thebutenes. The primary purpose of a solvent`is to avoidline plugging or`other-stoppages and to maintain the process smooth and continuous.`When `employinga concentrated feedstock,

rich in butadiene, as for example 98.5 percent pure butadiene asemployed in the process of my copending application, supra, it isdesirable and often necessary to employa solvent. In such instancespreferred solvents includethose which are inert with respectto thecatalyst and reactants and which are solvents for the reactants.Included among the'preferred solvents are saturated aliphatic andcycloaliphatic hydrocarbons containing from 4 to v10 carbon atoms,boiling preferably/above atmospheric temperatures, as for example,n-butane, n-pentane, n-licxane, isooctane, cyclohexane,methylcyclohexane, cyclooctane and thelike. Saturated petroleum naphthascan also be employed as well'as aromatic hydrocarbon The amount of`solvent employed `will be maintained in the range from 50 parts solventper 100 parts butadiene to 500 parts solvent per parts butadiene. Thesolvent can be added to the primary reactor or it can be added to theefliuentV as it is conveyed to or from the quiescent zone.

Catalystsapplicable for use in the present invention include` thealkalimetals such as sodium, potassium, or lithium; Vand alloys of the metalswith each other or -with calcium. A preferred catalyst is sodium metal.The

ing point of the alkali metal catalyst in an. atmosphere of driedoxygen-free nitrogen after which the freshly cut metal catalyst isadded. The dispersion medium is not a solvent for the catalyst itself.It is preferably a hydrocarbon solvent common to that employed in thereaction rmixureof a` nature as hereinbefore described. Thetemperature-is adjusted to about 20 F. abovethe melting point` of thecatalyst `and-the mixture vigorously agitated,

asaaeai as with an efficient stirrer operated at high speed (5,000 to10,000 R. P. M.) for a period usually ranging from 5 to 15 minutes oruntil a stable dispersion is produced. The system is allowed to cool toabout the melting point f the catalyst when agitation is stopped. Acatalyst thus prepared is ready for use in the process of thisinvention. If desired a dispersion stabilizer, for example, a selectedmercaptan such as tertiary-dodecylmercaptan, or carbon black, may beemployed in the preparation of the catalyst. In the former case theamount of mercaptan used is sufcient to give a quantity of alkali metalmercaptide equivalent to about 0.5 to 5.0 weight percent of the metalcatalyst employed, while in the latter case the amount of carbon blackintroduced is equivalent to from 2' to 20 percent of the weight of themetalcatalyst used. A more complete description of the catalystpreparation using dispersion stabilizers may be found in copendingapplications Serial Nos. 671,899 and 671,900, filed May 23, 1946, now U.S. Patents 2,483,886 and 2,483,887.

When operating within the range of catalyst quantity hereinbeforedescribed it is essential, to obtain a product of low viscosity, thatthe catalyst be finely dispersed, that is, that the average size of theparticles be small. It is essential that the average particle size ofthe catalyst be below 200 microns and desirable that it be below 100microns. It is frequently preferred that the average particle size ofthe catalyst be below 80 microns, say around 40 to 80 microns. When agiven concentration is employed, as the particle size of the catalyst isincreased polymers of higher viscosity are obtained.

The catalyst dispersion above described usually contains about to 35weight percent metal based on the dispersion medium employed in itspreparation. The amount of dispersion employed is such that the quantityof alkali metal catalyst charged to the reactor will be as hereinbeforestated.

In carrying out the process of my invention the reaction is started bycharging the reactants in the proper ratios to a closed reaction vesselfree from oxygen. The reaction is continued until the concentration ofthe polymer in the solvent reaches the desired level. This concentrationis in the range of at least weight percent but not in excess of 50weight percent in said reaction mixture exclusive of butadiene. Afterthe desired concentration level is reached reactants in the proper ratioare then continuously charged to said reaction vessel and an equivalentamount of reaction product is withdrawn and passed to the quiescentreaction vessel as hereinbefore mentioned. The temperature in thereaction vessel is in the range of from 150 to 225 F., preferably from175 to 210 F. Pressure is maintained suiciently high to provide liquidphase operation in the reaction vessel. A suitable pressure is in therange from about 0 to 200 p. s. i. g. or higher depending upon thereaction temperature selected. Constant vigorous agitation is suppliedto the reaction vessel. The conditions of temperature and pressuremaintained in the subsequent quiescent reaction zone are within theranges mentioned above. In some instances suitable heating means arenecessary in the quiescent Zone to maintain reaction temperatures. Thesum of the reaction periods in the initial reaction zone and quiescentzone is in the range of 1 to l0 hours.

When employing a butylene-butadiene feed to the process the product is aliquid polymer drying oil comprising liquid polybutadiene as theprincipal product and a small amount of alkylate formed by the reactionbetween butadiene and l-butene. The alkylate can be separated from theliquid polybutadiene by fractionation if desired.

Any suitable method for deactivating the catalyst can be used. In apreferred embodiment the catalyst is deactivated by treating theeiiiuent from the quiescent zone with a low molecular weight alcoholsuch as methanol. The amount of alcohol added will be in excess of thestoichiometric amount required to react with the catalyst. Low molecularweight alcohols which can be employed for this purpose comprise thosewhich contain preferably not more than 4 carbon atoms per molecule, forexample methanol, ethanol, l-propanol, 2-propanol, l-butanol, 2-methyl-l-propanol, 2-methyl-2-propanol, ethylene glycol, propyleneglycol, and butylene glycol. Mixtures of these alcohols can be employedif desired. Such alcohol treatment will preferably be elfected in theabsence of air.

Subsequent to the alcohol treatment to deactivate the catalyst thereaction mixture is washed with a suitable acid to remove the compoundsformed by interaction of catalyst and alcohol. Acids which can beemployed include preferably mineral acids such as sulfuric,hydrochloric, hydrobromic, nitric and phosphoric. Said acids areemployed in dilute aqueous form such as from 0.05 N to 1.0 N and areused in a suicient amount to maintain the pH of the treating solution inthe range of about 6.5 to 0.1 or below. In some instances an organicacid containing not more than four carbon atoms per molecule can beused.

Referring now in detail to Figure 1 of the drawings, disclosed is apreferred embodiment of my invention. A preferred feedstock is abutylene-butadiene mixture containing about 20 to 50 weight percentbutadiene with the remainder predominantly butenes. Such a feedstock isreadily obtainable as a C4 fraction from the distillation of theeiiiuent from the catalytic cracking of petroleum hydrocarbons. Such astream generally has acetylenic impurities removed before use in thepresent process in order to avoid fouling of the catalyst. In startingthe reaction feedstock from zone 10 and catalyst from zone 11 arecharged in the proper ratios, as hereinbefore d escribed, via lines 12and 13, respectively, to closed reaction vessel 14 which is maintainedfree from oxygen and the resulting mixture maintained in a highlyagitated condition. Extraneous solvent is not necessary due to thepresence of butenes in the feedstock. The reaction takes place underconditions of temperature and pressure, described more fullyhereinbefore, and proceeds until the concentration of polybutadienereaches at least 15 weight percent but not in excess of 50 weightpercent in the reaction mixture exclusive of butadiene. When such a con--centration is reached the catalyst and feedstock are continuouslycharged in the proper ratio and an approximately constant volume ofreaction mixture having a concentration of polybutadiene within theproper range is maintained by withdrawing an equivalent quantity ofreaction Vtains generally about 5 weight percent unreacted butadiene ona catalyst and polymer free basis. The conditions of temperature andpressure which obtain in quiescent zone 16 are essentially the same asthose in reaction vessel i4. The concentration of unreacted butadiene inthe e'iuent leaving quiescent zone 16 via line i7 is reduced at least to1.5 weight percent, and in all instances by at least 50 percent. Theeflluent in line 17 is admixed with methanol from Zone 20 via line 21 bymeans of pump 22 in order to deactivate the alkali metal catalyst anddissolve organo-metallic complexes. If a catalyst dispersion stabilizer,such as carbon black, has been employed, it is desirable to separatesolid impurities before alcohol treatment. Y However, it is necessarythat the reaction effluent does not come in contact with air beforealcohol treatment.

The alcohol-containing mixture is passed via line 23 to mixing zone 24'where it is mixed with acid from zone 25 via line 26. The acid isemployed in dilute aqueous form as hereinbefore described. The resultingmixture is continuously passed via line 30 to separation zone 31 wherethe aqueous phase containing alkali metal salts and other solublecatalyst residues is recovered via line 32. The organic phase containingbutenes, a very small amount of unreacted butadiene and drying oilpolymer asf/:esel

is passed via-line 331 to4 `fractionation zone 34. In fractionation zone34 butenespfromthe original.feedstock and containing less than 1.5weight percent butadiene 'are recovered asoverhead 4via line 35 andpassed to storage zone 36. These butenes are ina sutiiciently puriiiedstate for use` in other processes such as alkylation. If desired, thesmall amount of alkylate formed by reaction of the` butenes withbutadiene lcan be separated and passed to storage zone 40 via line 41.However, this is not required since the alkylate` is not necessarilyundesirable in the drying oil. The drying oil polymer, either with orwithout the alkylate, is recovered via line 42 and preferably `passed todecolorizing zone 43 Vfor suitable decolorization treatment. The cleardrying oil polymer is then passed to storage zone 44 via line 45.

Several alternative methods of operating 'are possible. For example,decolorization of the polymer can Vbe eiected before fractionation `invorder to have a less, viscous material to treat. Also, though lesspreferably, it is possible to separate the residual butylenes frompolymer after alcohol treatment but before acid treatment.

The following example is illustrative of the broad principle of myinvention in the reduction of unreacted butadiene to a level below 1.5weight percent and should not be construed as limiting.

EXAMPLE A run was conducted wherein 1,3-butadiene was polymerizedcontinuously to provide liquid polybutadiene of an average viscosity of600 Saybolt Furol seconds measured at 100 F. The apparatus consisted ofa 5 gallon autoclave which was employed as the reactor, connected inseries with a 1 gallon autoclave which was employed as a subsequentreaction zone constituting in principle the quiescent zone describedabove. Necessary control valves, etc., were also included in thereaction system.

The process was started by tirst preparing a 4 gallon batch of polymersolution in the 5 gallon reactor. The charge and reaction conditions forsaid initial batch were Vigorous agitation.

1Commercial grade. The principal diluent was methylcyclohcxane alongwith small quantities of other naphthenes, toluene, isolieptanes andisooctanes.

LDispersion of finely divided metallic sodium in xylene; concentrationof about 17 Weight percent sodium.

At the end of this stage of the reaction the 5 gallon reactor contained24.6 pounds of reaction mixture which was comprised of 40 weight percentof polybutadiene in n-heptane.

The process was then placed in continuous operation by the addition of amixture of 40 weight percent of 1,3- butadiene in n-heptane at a rate ofapproximately 2 gallons per hour. Sodium catalyst was added to thereactor at 30 minute intervals in charges equivalent to 1.25 Weightpercent of the butadiene charge rate. Immediately preceding each chargeof catalyst, approximately l gallon of reaction mixture was removed andrun to the l gallon autoclave where it was stirred for a short time toeffect further utilization of butadiene as evidenced by a drop inpressure to 2 p. s. i. g. Since the subsequent reaction was carried outin a batchwise manner the agitation therein actually simulates to someextent the same operation on continuous basis. However, agitation in acontinuous operation is unnecessary in the second reaction zone otherthan to eifect advantageous temperature control. Methanol was then'added to deactivate the catalyst. Data showing pressure drop evidencing.'furtherr L butadiene utilization `in. the; 1 gallon autoclavearewecorded below.-Y The ,temperature-inthe onefgallon i reactor -wasallowed; 1 to gdrop .about 110", F. which contributed in a small `amountto the pressure drop. However, the principal pressure drop waseftectedby butadiene conversion.

I gallon reactor Initial Final Inter- Charge Number Pressure, Pressure,val,

p. s. i. g. p. s. i. g. Minutes After l0 minutes conditions in the 5gallon reactor lined out to a reaction temperature of 202-206 F. andpressure of 13-19 p. s. i. g. Data showing conditions at shut down arerecorded in the following table.

The improvement of the present invention is further illustrated by thesedata wherein at 234 minutes the pressure dropped from 13 p. s. i. g. to3 p. s. g. Within a 15 minute interval after the butadiene feed was cutolf. This pressure of 3 p. s. i. g. represents a butadiene content ofabout 1.1 weight percent based on n-heptane.

Accrued Butadiene- Heptane Charge,

pounds 13 (Butadene content at this pressure was 1.1 weight percent1based on heptane).

205 Charging Stopped... 202

1 Percent butadiene was extrapolated from the curve (Figure 2), saidcurve was derived by a study of the pressures exhibited by a1,3-butadiene-n-heptane-system at an average temperature of 202 F.Incremental amounts of 1,3-butadiene were charged to an autoclavecontaining 18 pounds of n-heptane and the pressure of the system wasthen read and plotted against Weight percent butadiene. Thus, a givenpressure corresponds to a definite butadiene concentration. For example,a pressure of 3 p. s. i. g. represents a concentration of 1.1 weightpercent of 1,3-butadiene.

Summation Continuous reaction time hrs-- 3.9 Average residen-ce time inve gallon reactor hrs 1.98 Average residence time in l gallon reactormin 8 While this invention has been described and exemplied in terms ofits preferred embodiment those skilled in the art will appreciate thatmodications may be madeV without departing from the spirit and scope ofthe invention described herein.

I claim:

1. A continuous method for the production of a liquid polybutadienedrying oil free from solid polymers which comprises continuouslymaintaining approximately constant volume of reaction mixture comprisinga highly agitated stable dispersion of nely divided alkali metalcatalyst in a body of hydrocarbon solvent containing butadiene andpolybutadiene in a closed reaction vessel at a temperature in the rangeof to 220 F., introducing an impure butadiene polymerization feedcontaining a hydrocarbon solvent and catalyst having an average particlesize less than 200 microns into said body of liquid reaction mixture,withdrawing equivalent quantities of reaction mixture containing anamount of unreacted butadiene of about 5 weight percent on a catalystand polymer free basis to maintain an approximately constant volume at arate permitting the formation and maintenance of polybutadiene in aconcentration of at least 15 aaaaeal 7 weight percent in said reactionmixture exclusive of butadiene, the quantity of the catalyst employedbeing not in excess of 2.0 parts by weight per 100` parts of butadieneemployed, continuously passing said withdrawn reaction mixture into oneend of a relatively quiescent tubular reaction zone having a length todiameter ratio in the range of 2:1 to,100:1 and a volume sulicient toa1- low a residence time'therein in the range of 5 minutes to 5 hours,withdrawing from the opposite end of said quescent zone a quantity ofreaction mixture containing no more than 1.5 weightpercent unreactedbutadiene on a catalyst and polymer'free basis, continuously deactivat-Ving alkali metal and metallo-organic complexes contained in said mixtureby contactingwithfalowmoleculr'weight alcohol having not morethan4-carbon atoms per molecule, continuously separating,'thefresultingdeactivated materials from the mixture by washing with a dilute aqueousmineral acid,1 continuously separating solvent References Cited in thele of this patent y UNITED STATES PATENTS Rothrock Dec. 2, 19412,527,768 Schulze et al. Oct. 3l, 1950 2,603,655 Strain July 15, 19522,631,175 Crouch Mar. l0, 1953 2,701,780 Nelson et al. Feb. 8, 19552,728,801 Iaros et al. Dec. 27, 1955 UNITED STATES PATENT OFFICECERTIFICATE OF CORRECTION Patent NO. 2,826,621 March 1958 Willie' W.Crouch It is hereb;T certified that error appears in the printedspecification of the above numbered patent requiring correction and thatthe said ,Letters Patent should read las corrected below.

Column 6, line 66, for n.2.20" F." read 2250 F. column 7,1116@ lo, fory"quescent" read quiescent -v. v

Signed and sealed this 27th day o' May 1958.

(SEAL) Attest:

KARL H" AXLINE ROBERT c. wATsoN Attesting Officer (burnissioner ofPatents

1. A CONTINUOUS METHOD FOR THE PRODUCTION OF A LIQUID POLYBUTADIENEDRYING OIL FREE FROM SOLID POLYMERS WHICH COMPRISES CONTINUOUSLYMAINTAINING APPROXIMATELY CONSTANT VOLUME OF REACTION MIXTURE COMPRISINGA HIGHLY AGITATED STABLE DISPERSION OF FINELY DIVIDED ALKALI METALCATALYST IN A BODY OF HYDROCARBON SOLVENT CONTAINING BUTADIENE ANDPOLYBUTADIENE IN A CLOSED REACTION VESSEL AT A TEMPERATURE IN THE RANGEOF 150 TO 220*F., INTRODUCING AN IMPURE BUTADIENE POLYMERIZATION FEEDCONTAINING A HYDROCARBON SOLVENT AND CATALYST HAVING AN AVERAGE PARTICLESIZE LESS THAN 200 MICRONS INTO SAID BODY OF LIQUID REACTION MIXTURE,WITHDRAWING EQUIVALENT QUANTITIES OF REACTION MIXTURE CONTAINING ANAMOUNT OF UNREACTED BUTADIENE OF ABOUT 5 WEIGHT PERCENT ON A CATALYSTAND POLYMER FREE BASIS TO MAINTAIN AN APPROXIMATELY CONSTANT VOLUME AT ARATE PERMITTING THE FORMATION AND MAINTENANCE OF POLYBUTADIENE IN ACONCENTRATION OF AT LEAST 15 WEIGHT PERCENT IN SAID REACTION MIXTUREEXCLUSIVE OF BUTADIENE, THE QUANTITY OF THE CATALYST EMPLOYED BEING NOTIN EXCESS OF 2.0 PARTS BY WEIGHT PER 100 PARTS OF BUTADIENE EMPLOYED,CONTINUOUSLY PASSING SAID WITHDRAWN REACTION MIXTURE INTO ONE END OF ARELATIVELY QUIESCENT TUBULAR REACTION ZONE HAVING LENGTH TO DIAMETERRATIO IN THE RANGE OF 2:1 TO 100:1 AND A VOLUME SUFFICIENT TO ALLOW ARESIDENCE TIME THEREIN IN THE RANGE OF 5 MINUTES TO 5 HOURS, WITHDRAWINGFROM THE OPPOSITE END OF SAID QUESCENT ZONE A QUANTITY OF REACTIONMIXTURE CONTAINING NO MORE THAN 1.5 WEIGHT PERCENT UNREACTED BUTADIENEON A CATALYST AND POLYMER FREE BASIS, CONTINUOUSLY DEACTIVATING ALKALIMETAL AND METALLO-ORGANIC COMPLEXES CONTAINED IN SAID MIXTURE BYCONTACTING WITH A LOW MOLECULAR WEIGHT ALCOHOL HAVING NOT MORE THAN 4CARBON ATOMS PER MOLECULE, CONTINUOUSLY SEPARATING THE RESULTINGDEACTIVATED MATERIALS FROM THE MIXTURE BY WASHING WITH A DILUTE AQUEOUSMINERAL ACID, CONTINUOUSLY SEPARATING SOLVENT FROM POLYMER, ANDRECOVERING A LIQUID POLYBUTADIENE DRYING OIL FREE FROM SOLID POLYMER.